The prior art is well documented with examples of prosthetic implant devices, such as particular useful as replacement joints. The objective of such devices is to replicate, to the degree possible, the normal functionality of a user's joint while providing for a degree of ongoing effectiveness and durability.
A problem associated with prior art artificial joint implants is the eventual wearing away of either or both of the abrading wear surfaces associated with the prosthetic joint implants. This problem is often compounded in situations where a normal (remaining) bone end surface defines a first half of a joint assembly, this arrayed opposite a prosthetic installed artificial wear surface, such as defining a part of an artificial implant bone or alternatively fashioned to a worn end of an opposite existing bone, and such that first and second different materials with different wear properties result.
Noteworthy examples of joint constructions drawn from the prior art include the bone joint endo-prosthesis of Zeibeg et al., U.S. Pat. No. 4,170,794, and which includes a spherical body interiorly apertured to receive a shaft spigot. A spreader includes a material which, upon wetted, swells. The material is wrapped over the spigot such that radial expansion provides shaping or profiling of the spreader for effective retention in a joint zone.
A non-medical example of a ball and joint socket is disclosed in Smith, U.S. Pat. No. 4,431,328, and which teaches an enlarged diameter half ball member disposed in a socket member and having a recess in which is engaged a biasing insert member made of a resilient or elastomeric material placed under compression during assembly of the joint. The joint bearing surfaces are elastically pre-loaded in an appropriate direction which causes firm engagement of the bearing surfaces in mutual engagement, preventing play and rattle of the joint and compensating for wear.
Additional examples of knee joint wear reducing implants include the prosthesis shown in Koch et al., U.S. Pat. No. 5,197,987 in which a tibia metal plate and a femur attached portion sandwich there-between an intermediate plastic part. Support members of hard material are distributed in the bearing surface of the intermediate plastic part, such as to receive the femur part thereon. The bearing surfaces of the support members are integrated in the bearing surface of the intermediate part and are provided with dual surfaces to receive different bearing surfaces of the femur part, each of which can exhibit a different radius of curvature.
Other noteworthy examples of implant assemblies drawn from the prior art include the artificial implant of Salehi et al., U.S. Pat. No. 6,645,251, this exhibiting reduced wear areas in the form of indentations, grooves, dimples, patterns, holes channels and slots.